Patent GB-1189468-A (GB)
Title: Integral Photography
IPC: G03B35/24
Filed: 1967-11-30
Abstract: 1,189,468. Three dimensional photography. RLM RESEARCH CORP. Nov.30, 1967 [Dec.12, 1966], No.54510/67. Heading G2A. A method of three dimensional photography comprises the three steps of (a) recording a scene through a lenticular network on to a photo-sensitive layer on one focal surface of the network, (b) placing the photo-sensitive layer, after development, at one focal surface of a second lenticular network, having a second photo-sensitive layer at the other focal surface, and projecting the image from the first photo-sensitive layer on to the second layer, (c) placing the second layer, after development, at a focal surface of a third lenticular network (whereby viewing the image produced by illumination through the third network produces a three dimensional orthoscopic virtual image). Fig.1 shows a lenticular network of closely packed lenslets in the shape of part-spherical convex elements, formed on both sides of a sheet 20 which is preferably of a transparent polyester resin having a refractive index of 1.56 or more. The spacing of the lenslets may lie in the range 0À04"-0À1", according to the overall size of the picture, and the arrangement is preferably hexagonal Fig.2 (not shown). The photo-sensitive sheet 28 is embossed between pressure dies to reproduce the lenticular network. The first step is illustrated by Fig. 5, which shows an enlarged view, in cross-section, of a single pair of opposed plano-convex lenslets 42, 46. The lower lenslet 46 has in close contact therewith the photo-sensitive sheet 54, embossed to the same shape. Between the planar faces of the two lenslets is a metal sheet 48 having a diaphragm aperture 52. The flat areas between adjacent lenslets 42 are covered by an opaque mask 45. An initial exposure of the scene is made through the upper and lower networks on to the sheet 54. This produces an assembly of images which, when projected, would form in space a summation real image which is a three dimensional but pseudoscopic duplicate of the original scene. After processing, to render the images visible, the exposed film 54 is positioned in register with a second lenticular network Fig.6 for the second, or transposing, step. On the planar surface of each lenslet 46 (which are identical with the lenslets 46 of Fig. 5) is a sheet 56 having an opaque layer 58 with a diaphragm aperture 60 and, opposed to lenslet 46, a lenslet 62. Spaced from lenslet 62 is another embossed photo-sensitive film sheet 66. The radius of the lenslets 62 is so chosen, in relation to the various indices of refraction, that the images on film sheet 54 may be brought into proper register and focus on the film sheet 66. The layer 58 may have adjacent field-limiting apertures. Sheet 66 is now exposed by illumination through film sheet 54, the images on sheets 54 and 56 being at conjugate surfaces of the lenslets. Film sheet 66 is now removed, developed, and positioned in intimate registering contact with the rear convex surfaces of a third lenticular network 70 Fig.7, and may be cemented thereto. This constitutes the third step. For viewing, the assembly is illuminated from the far side, and viewed through the lenslets 72, when the original scene is now seen as a wide-angle summation virtual image which is three dimensional and orthoscopic. As the viewing angle changes, the observer will see different stereoscopic views of the same scene. In a modification, Figs.8, 9, 10 (not shown), the initial exposure is formed, through the lenticular network, on flat film, while the second film is embossed and viewed through a further lenticular network as before. Figs.11, 12, 13 (not shown) illustrate an elaboration of the embodiment of Figs.8, 9, 10 (not shown). In a further modification, Figs.14, 15, 16 (not shown), the spherically embossed film is spaced apart from the lenticules of the network. In a further modification, Figs.17, 18, 19 (not shown), a single or identical lenslet sheet may be used for all three stages.